DHCP issue on a RT-AC88U

[fredfit]

Hello all,
Thank you for welcoming me in this forum.

I recently bought a RT-AC88U router which DHCP range starts at 192.168.1.2 and ends at 192.168.1.254.
I mainly have no issues with the devices that I declared with a static IP but the DHCP sometimes attributes a 192.168.100.x IP address to some dynamic IP devices on my network !
I'm running Asuswrt-Merlin v386.3.2 (latest one).
I'm currently facing this issue with a Synology NAS (that I see with IP 192.168.100.110 using "Advanced IP scanner" tool). Since the access to its configuration can only be done through the network, I cannot give it a static IP address ...

I would really appreciate if someone could help me on this.
Thanks ! (and sorry for my english )

Fred/Paris/France

 

[ColinTaylor]

Is your NAS configured as a DHCP server?

Do you have any other routers or servers on your LAN that might be running a DHCP server?

 

[fredfit]

Thank you Colin for your help !
I finally managed to find the root cause of my issue: I had a Wifi repeater (D-Link DIR-505) connected to my LAN. He was probably acting as a second DHCP server and put the mess in the IP addresses distribution.
After having removed it, it seems that the DHCP behaviour of the Asus router is back to normal.
I also succeeded in putting my Syno with a static IP address.
I cross my fingers